Improvement in furnace-grates



' c. HOFFMANN.

- Furnace-Grates.

Patented S ept. 8,1874.

UNITED STATES PATENT OFFICE.

CARL HOFFMAN, OF NEW YORK, N. Y.

IMPROVEMENT IN FURNACE-GRATES.

Specification forming part of Letters Patent No. 154,866, dated September 8, 1874 application filed August 19, 1874.

To all whom it may concern:

Be it known that I, CARL HOFFMAN, of the city, county, and State of New York, have invented a certain new and useful Improvement in Furnace-Grates, of which the following is a specification:

This invention relates to an improvement on a grate-bar for which a patent was granted to me January 23, 1872, No. 123,018; and it consists in a furnace-grate composed of gratebars provided on their sides with oblique ledges, which are so situated that when two or more bars are placed side by side the ledges of one grate-bar interlock with those of the adjoining bar or bars, leaving air-channels between said ledges, whereby a grate is formed,

on which comminuted coal or other inferior fuelcan be consumed with advantage. Each of the grate-bars is provided at one end with a recess to catch over a traverse. so that the expansion of all the grate-bars will take place from one and the same end, and that the proper position of the oblique ledges of one grate-bar toward those of the adjoining bar or bars cannot be disturbed.

This invention is illustrated in the accompanying drawing, in which- Figure 1 represents a longitudinal section. Fig. 2 is a plan or top view of the same. Fig. 3 is a transverse section of one of the gratebars.

Similar letters indicate corresponding parts.

In these drawings, the letter A designates a furnace-grate, which is composed of gratebars B B, &c. Each of these bars is provided on its sides with oblique ledges b b, &c.,

which are inclined at an angle of about fortyfive degrees toward the surface of the bars, and which are so situated that, when the bars B B are placed side by side, as shown in Fig. 2, the ledges b of the bar B will interlock with the ledges b of the bar B, leaving channels cl between the adjoining ledges, through which air can be forced into the fire. The web 0 of each bar is chamfered off on both sides, so that the top edge of said web becomes quite narrow, thereby giving the air forced up through the channels d free access to the fuel spread on the grate.

In order to prevent the adjoining gratebars from losing their proper relation toward each other, I provide the same with recesses e, which catch over a traverse, f, secured in the furnace-wall. Said recesses are all made at the corresponding ends of the grate-bars, so that the expansion of the gratebars must take place from the same end, and that the air-channels d between the ledges of the adjoining grate-bars will not be disturbed by such expansion.

The principal advantage of the above-described arrangement of the ledges b I) over those described in my patent No. 123,018 is, that the distance between the ledges on each grate-bar is materially increased, and thereby the operation of casting said grate-bars is facilitated.

The air-channels d extend clear to the ends of the grate-bars, so that said ends are not exposed to an excessive heat. By the air passing through the air-channels all parts of the grate-bars are kept sufficiently cool to prevent them from' getting burnt.

The sides of the grate-bars which adjoin the furnace-wall are provided with an increased number of ledges, so as to render the airchannels between them sufficiently narrow to prevent the fuel from passing down through them.

It will be noticed that the upper surface of this grate is left smooth or fiat, so that the fire-hook or poker Will pass freely over the same.

The last grate bars on each side of the grate are either made with a double set of ledges on their outsides, or they are left flat, representing one-half of the ordinary gratebars cut through in the. direction of their length.

I disclaim everything shown and described in my patent N 0. 123,018.

What I claim as new, and desire to secure by Letters Patent, is-

A furnace-grate composed of grate-bars, with interlocking oblique ledges, and intervenin g air-channels 01, substantially as shown and described.

In testimony that I claim the foregoing I have hereunto set my hand and seal this 18th day of August, 1874.

CARL HOFFMANN.

Witnesses: 7

W. HAUFF, E. F. KASTENHUBER. 

